I understand you disagree with the whole thing but blockchain has a lot of uses already. Most obvious ones are storing money or investment and transferring money. It factually works amazing for these. Assuming you believe in capitalism, people won’t put such enormous amounts of money on something if it has no use. Speculation also applies to stocks in the same way, there is no world where nvidia should be priced like this but people have some view on it and it effects the price. Same idea with blockchain, there are already use cases and it is expanding constantly. Also there is a ton of investment going into research of development of it, there is no reason why people shouldn’t invest in it by buying coins, it is factually a good investment so far if you are able to hold for long periods of time